mjit_worker.c: pass -lgcc to GCC platforms

using `-nodefaultlibs -nostdlib`.

I assume libgcc is needed when we use -nostdlib, and it's linked on some
platforms but not linked on some platforms (like aarch64, and possibly
AIX as well) as said in https://wiki.osdev.org/Libgcc :

> You can link with libgcc by passing -lgcc when linking your kernel
with your compiler. You don't need to do this unless you pass the
-nodefaultlibs option (implied by -nostdlib)

Also note that -nostdlib is not strictly needed (rather implied
-nodefaultlibs is problematic for Gentoo like Bug#15513, which will be
approached later) but helpful for performance. So I want to keep it for
now.

[Bug #15522]

I'm not trying to add `-nodefaultlibs -nostdlib` for AIX in this commit
because AIX RubyCI is dead right now, but I'll try to add them again
once RubyCI is fixed.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66812 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

mjit_worker.c

@@ -268,14 +268,14 @@ static const char *const CC_DLDFLAGS_ARGS[] = {
 };
 
 static const char *const CC_LIBS[] = {
-#if defined(_WIN32) || defined(__CYGWIN__) // mswin, mingw, cygwin
-    MJIT_LIBS
+#if defined(_WIN32) || defined(__CYGWIN__)
+    MJIT_LIBS // mswin, mingw, cygwin
 #endif
-#if defined(_WIN32) && defined __GNUC__ && !defined __clang__ // mingw
-    "-lmsvcrt",
-#endif
-#if (defined(_WIN32) || defined(__CYGWIN__)) && defined __GNUC__ && !defined __clang__ // mingw, cygwin
-    "-lgcc",
+#if defined __GNUC__ && !defined __clang__
+# if defined(_WIN32)
+    "-lmsvcrt", // mingw
+# endif
+    "-lgcc", // mingw, cygwin, and GCC platforms using `-nodefaultlibs -nostdlib`
 #endif
     NULL
 };